Compressed air tanks for utility vehicles are known from the general state of the art and are used for various functionalities, in particular for supplying compressed air to air suspensions of utility vehicles.
Compressed air tanks can be used in utility vehicles to supply a multiplicity of consuming devices. In addition to compressed-air brake systems and air suspensions, these consuming devices can also take the form, for example, of life-saving systems, (for example airbags) or systems which alter the tire pressure of utility vehicles. Pressure tanks are used, however, not only in the field of utility vehicles and passenger vehicles, but also in respect of other vehicles, for example rail vehicles.
A pressure tank for supplying vehicles, in particular utility vehicles, with a pressurized gaseous medium is known, for example, from DE 20 2005 018 579 U1.
Traditional pressure tanks have a tubular or cylindrical peripheral wall (casing), the open end faces of which are sealed, generally welded, with appropriate caps (outer bases). A cavity for storing the designated gas is thereby formed. The cavity can be loaded and/or unloaded via ports or bores in the casing or in the outer bases.
DE 20 2005 018 579 U1 describes an advantageous embodiment of a compressed air tank such that at least one outer base is configured integrally with the casing. If necessary, both outer bases can also be configured integrally with, respectively, a part of the peripheral wall.
In general terms, compressed air tanks must be able to withstand mechanical loads resulting from internal or external pressure, as well as further mechanical, physical (temperature) and chemical loads. A commonly used material for the manufacture of appropriate pressure tanks is steel. Steel tanks have in essence the advantage of high mechanical strength, and thus high compressive strength, and also good temperature resistance. On the other hand, the chemical resistance of steel with respect to corrosive substances is rather poor. Steel tanks are also relatively susceptible to external weather influences, so that an additional outer and, if necessary, inner coating or paint coating is generally provided. In the prior art, the inner coating of a compressed air tank is obtained by virtue of a so-called wet paint coating, which does not however yield satisfactory results and, in particular, cannot be applied in a cost-effective manner. In the known compressed air tanks, moreover, the problem exists that, at the junction between the outer base and the peripheral wall (casing), a so-called dirt-collecting edge (also termed a chemical edge) is formed. Particles, or in general terms impurities, stick to this edge, which then hinder or prevent the application of an inner coating there. The dirt-collecting edge which is formed when the outer base is connected to the casing can be seen, for example, from FIG. 6 of DE 20 2005 018 579 U1. The outer base has in general an inwardly tapered bead (lead-in chamfer), over which the casing or the peripheral wall is slid. A contact region is thereby created, which is then next welded by a MAG welding process such that the outer base is connected to the casing.
In the compressed air tanks known from the prior art in which both outer bases are configured independently from the casing, two such dirt-collecting edges are consequently formed. Although the embodiment according to FIG. 1 of DE 20 2005 018 579 U1 avoids such dirt-collecting edges, it does however demand a higher cost for the manufacture of the sleeves.
A drawback of the MAG welding process for connecting the outer base to the casing consists in the MAG welding process being relatively slow.
A further problem with the compressed air tanks known from the prior art consists in the fitting of sleeves onto or around the bores in the outer bases or in the casing. The bores serve various purposes, for example the connection of lines. Such connections can be seen, for example, from FIG. 1 of DE 200 23 422 U1, which shows a plastic compressed air tank. In a configuration of a metal pressure tank, it is generally provided to weld sleeves onto the bores in the outer base or the casing. Here, the sleeves are again welded on by a MAG welding process. A drawback with this is that the welding-on of the sleeve engenders a high cost, since the MAG welding process is relatively slow and welding material, moreover, is necessary.